As a resin molding device, an injection molding device has been widely known and popular in general. A technique to remove a resin molded product created by an injection molding device from a mold with an air ejector (see Japanese Patent Laid-Open Application Publication No. 2001-9880, for example) is also well known. After injection molding, a resin molded product is tightly attached in a vacuum state to the surface of the mold by the pressure applied by the injection molding. The vacuum state between the mold and the resin molded product is released by air injected from the air ejector to thereby remove the resin molded product from the mold.
There is an air ejector comprising a movable valve (rod) accommodated in an air passage. The movable valve moves forward and backward in a direction of air injection to open and close an air outlet from which air blows. The movable valve is generally biased by a bias member such as a spring to be accommodated in the air passage to close the air outlet. When air is supplied to the air passage, the movable valve is moved to protrude from the air outlet, thereby opening the air outlet. Also, the movable valve protrudes from the air outlet to a molding space along with the injected air to push out the resin molded product. To remove the resin molded product from a mold, the movable valve is moved towards the resin molded product by pressure of the air supplied in the air passage to open the air outlet. Thereby, the vacuum state between the resin molded product and the surface of the mold is released by the air injection from the air outlet and the resin molded product is pushed out by the protrusion of the movable valve from the air outlet and separated from the mold. When the air supply is stopped, the movable valve is returned to the initial position by the bias force of the bias member to close the air outlet. Then, the injection molding of the resin molded product and the removal of the mold continue.
However, a problem may arise that when the air supply is stopped, the movable valve becomes stuck and is not returned to the initial position for some reason such as an operation failure of the bias member. Such a returning failure of the movable valve may cause a breakage of the mold or the movable valve when the mold is clamped next. Further, melted resin may enter the air passage from the air outlet, causing the operation failure or breakage of the air ejector. Therefore, it is required to develop a resin molding device and method to be able to quickly and surely detect the operation failure of the air ejector and promptly recover the air ejector to be in a normal state.